Darius the Great Conquers the Indus Valley

Darius the Great of Persia explored and added the Indus Valley to his empire, allowing commerce and ideas to flow easily between east and west.

Summary of Event

The Persian Empire under its Achaemenid rulers (705-330 b.c.e.) was the largest political entity in the Near East until Alexander the Great (356-323 b.c.e.) briefly united all the countries from Greece to India. No historical narratives composed by the Persians have survived, and it is likely that none were ever written. However, Persian monarchs often commissioned monumental inscriptions to be placed in public places at decisive moments during their reigns. These impressive inscriptions functioned as political propaganda, lauding the ruler and his most recent public works and conquests. They often concluded with a list of the provinces subject to Persian rule at the time. The growth of the empire is related in these lists. Cyrus the Great
Darius the Great

Greek writers constitute the only other major source of information about the Achaemenid Empire. Chief among these is the historian Herodotus (c. 484-c. 425 b.c.e.), whose Historiai Herodotou (c. 424 b.c.e.; The History, 1709) is devoted to the rise of Persia and its relations with Greece. A few other Greek writers provide occasional nuggets of information, as do some books in the Hebrew Bible.

The Persian Empire included a part of the Indus River Valley on its eastern frontier almost from the beginning. The first great Achaemenid king, Cyrus the Great, created an empire in the area now occupied by Iran and Iraq before expanding both east and west. By 545 b.c.e. he had extended his holdings in the east to, or nearly to, the banks of the Indus River, east of modern Kabul and Peshawar. Cyrus named this new eastern province Paruparaesanna, “the land beyond the mountains.” Later, it was called by its native name, Gandhara.

After Cyrus the Great’s death in 530 b.c.e., his son Cambyses II (r. 529-522 b.c.e.) became king. Cambyses reigned for only eight years before dying under mysterious circumstances. In the ensuing chaos, Darius the Great, a distant relative of Cyrus without a direct claim to the throne, used intrigue and assassination to obtain the kingship, which he held from 522 to 486 b.c.e.

Darius the Great.

(Library of Congress)

The new king’s first order of business was to quell the uprisings that had begun after Cambyses died. Once his base of power was secure, Darius turned his thoughts to expansion. He seems to have been both eager for fame as a great conqueror and practical in his desire to extend the commercial horizons of his empire. In the west, his failure to seize the Greek mainland is well known and forms the focal point of Herodotus’s work. The Persian defeat in 490 b.c.e. on the plain of Marathon became the rallying cry for the Greek city-states ten years later when they expelled Darius’s successor Xerxes I (r. 486-465 b.c.e.) and forever ended the threat of Persian domination in Greece.

In the east, Darius’s conquests seem to have had an additional motivation: the need to protect his holdings from invaders from the north. Herodotus recounted fabulous stories of gold, apes, peacocks, ivory, and other exotic goods that may also have influenced Darius to press farther south along the Indus River in search of trade routes. Because there is no Indian equivalent of Herodotus, evidence regarding Darius’s eastern campaigns remains sketchy. The details of his movements have generated much scholarly disagreement.

Herodotus states clearly that the Persian king commissioned an expedition to sail down the Indus River from some northern point in order to find out where it debouched into the Indian Ocean. Trustworthy sailors, including a Greek-speaking Persian subject named Scylax, then returned home, probably traveling along the Iranian coast, around the Arabian peninsula, and back to a port in Egypt. As a result of the information gained by this expedition Darius took over a new province somewhere east or south of Gandhara and proceeded to make use of the Indian Ocean, presumably for trade.

One of the few aspects of the Indian campaign that can be stated with certainty is its date. In 520 b.c.e., after he had reunited dissident factions in Persia, Darius commissioned a massive trilingual inscription to commemorate his triumph. It still stands today on a cliff at Bisitun, high above the road from Babylon to Ecbatana (now Hamadan, Iran), one of the ancient capitals of Persia. The list of subject provinces at the end includes Gandhara as the easternmost province. The inscription carved to commemorate Darius’s building of a wall around Persepolis in 518 b.c.e. contains Gandhara and a new eastern province, Hindush. This province, whose name reproduces the Persian pronunciation of “Indus” (from which derives the word “Hindu”), must have been acquired sometime between 520 and 518 b.c.e.

The location of the newly conquered territory is in dispute, but it clearly lay somewhere along the Indus River. Persian dominion in the region seems to have been limited to the area along the Indus River and its tributaries. It did not extend to the Ganges River Valley, at that time a thriving region in northern India. Most scholars feel that the new Persian possession was the area around the mouth of the Indus River, known today as the province of Sind in Pakistan. A few believe that Darius proceeded northeast of the existing province of Gandhara and conquered territory there. This latter view makes the expeditionary voyage irrelevant to the military action.

Herodotus states clearly that Darius sent the expedition before beginning his takeover of the new province, and most agree. Some scholars feel that a naval expedition unprotected by the Persian military force would not have survived hostile natives, but it is not known how the inhabitants of the Indus Valley at that time would have responded to the Persians. It seems most likely that before mounting an invasion the cautious Darius would have sent out scouts to explore the area, both for its purported wealth and for information that would help his forces succeed.

Little is known about the administration of the province of Hindush while under Achaemenid dominion. The Persians did build forts along the rivers in their eastern holdings, and there is evidence for a fort on the Indus that may have housed the provincial governor. Hindush contributed a massive amount of gold as tribute to the Persian treasury: Herodotus says it made the largest contribution of all the provinces, 360 talents of gold dust per year, nearly half the crown’s revenues. Later, Indian soldiers from this province, both on foot and in chariots, were conscripted to fight for Persia in Greece.

How long Persian hegemony lasted in the Indus Valley is unclear. Hindush appears in the province lists of Darius’s successor Xerxes and may still have belonged to the Persians in the fourth century b.c.e. if the identification in the biblical book of Esther of the Persian king Ahasuerus with Artaxerxes II (405-359 b.c.e.) is correct. Persian control must have slipped soon after that, for, when Alexander crossed the Indus River in 326 b.c.e., he found local kings, not Persian governors, awaiting him.


The Persian incursion into the Indus Valley established much broader communications between east and west. Such contact had existed for millennia in the form of commercial relations. Now a well-organized, efficient administration linked the Persian capital and its territories. The results were felt in both India and the West.

In the East, stamped coins came into use in the Ganges Valley shortly after the arrival of the Persians in the lower Indus Valley. Scholars believe the Aramaic language and letters, used by the Persians as a sort of lingua franca, were probably introduced into India around the same time. Later Sanskrit texts suggest that Babylonian astrological writings were translated into Indian languages around 500 b.c.e. The first inscriptions found in India, of a monumental type similar to the records of the Achaemenid kings, date from the reign of the emperor Aśoka (r. c. 273/265-238 b.c.e.). The script used in these monuments is consistent with a development from Aramaic letters over the course of several hundred years.

Eastern ideas had an equally great influence on the West. Concepts of transmigration of souls, strikingly similar to Indian ideas about reincarnation, appear about this time in the teachings of the early Greek philosophers, especially Pythagoras (c. 580-c. 500 b.c.e.). They influenced many later Greek and Near Eastern religious ideas.

The desire to facilitate access to the gold of India, and presumably also to India’s trading partners to the east, may have persuaded Darius to reopen an Egyptian canal that is the ancestor of the modern Suez canal. Originally created by the Egyptian pharaoh Seti I (c. late fourteenth century-c. 1279 b.c.e.), it was cleaned of silt by Pharaoh Necho II (610-595 b.c.e.) but fell into disuse again. Ancient sources are divided in their opinion as to whether Darius actually used the canal. However, most believe he did, and Darius’s own inscriptions state proudly, “This canal was dug.”

A book titled Periplus (voyage around by sea) written by Scylax, a member of Darius’s exploratory expedition down the Indus River, became the foundation for two new genres of Greek writing, geography and ethnography. The book influenced all later Greek historians, including Herodotus, and through them later historical writing. It remained the source for all Greek knowledge about India until the time of Alexander the Great.

Further Reading

  • Cook. J. M. The Persian Empire. New York: Schocken Books, 1983. Covers the growth of the Achaemenid Empire through the conquest of Alexander. Many photographs and maps.
  • Herodotus. The Histories. Translated by Robin Waterfield. New York: Oxford University Press, 1998. Useful and extensive notes. The description of Darius’s conquest of the Indus appears in book 4, chapter 44.
  • Kuhrt, Amelie. The Ancient Near East, c. 3000-330 b.c.
    2 vols. New York: Routledge, 1995. Volume 2, chapter 13, covers the Achaemenid Empire. Detailed bibliography.
  • Olmstead, A. T. History of the Persian Empire. Chicago: University of Chicago Press, 1948. Somewhat outdated but still the starting point for all histories of the Achaemenid Empire. Photographs and maps.
  • Pingree, David. From Astral Omens to Astrology, from Babylon to Bikaner. Rome, Italy: Serie Orientale, 1997. Presents the transmission of celestial omens, astronomy and astrology in the area from Greece to India as a model for the way many other kinds of knowledge were shared in antiquity.

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